Turbomachine rotor construction

ABSTRACT

A ROTOR WHEEL FOR USE IN A TURBOMACHINE WHEREIN THE CIRCUMFERENTIALLY ARRANGED BLADES ARE PROVIDED WITH EXTERNALLY THREADED SHANK PORTIONS FOR MATING WITH INTERNALLY THREADED OPENINGS PROVIDED WITHIN THE SUPPORTING DISC. INTERMEDIATE PORTIONS OF ALL BUT TWO BLADES HAVE AT LEAST ONE PERIPHERAL SECTION REMOVED WHILE ONE OF THE REMAINING TWO HAS NO REMOVED SECTION AND THE OTHER HAS TWO SHANK SECTIONS REMOVED SO AS TO PERMIT SEQUENTIAL ASSEM-   BLY OF THE BLADE IN A CIRCUMFERENTIAL PATH ABOUT THE DISC IN A PREDETERMINED MANNER.

Feb. 23, R, E HANSEN TURBOMACHINE ROTOR CONSTRUCTIOS Filed Feb. 24, 1969INVENTOR. RAYMOND E. HANSEN.

ATTORNEY.

United States Patent 3,565,547 TURBOMACHINE ROTOR CONSTRUCTION RaymondE. Hansen, New Alexandria, Pa., assignor to Carrier Corporation,Syracuse, N.Y., a corporation of Delaware Filed Feb. 24, 1969, Ser. No.801,687 Int. Cl. F01d /32 US. Cl. 416204 2 Claims ABSTRACT OF THEDISCLOSURE A rotor wheel for use in a turbomachine wherein thecircumferentially arranged blades are provided with externally threadedshank portions for mating with internally threaded openings providedwithin the supporting disc. Intermediate portions of all but two bladeshave at least one peripheral section removed while one of the remainingtwo has no removed section and the other has two shank sections removedso as to permit sequential assembly of the blade in a circumferentialpath about the disc in a predetermined manner.

BACKGROUND OF THE INVENTION In a turbomachine such as a turbine oraxial-flow compressor, fluid under pressure is directed against anannular array of blades or buckets disposed about the periphery of anannular support member secured to a power shaft. The fluid subjects theblades to severe vibrational stress and also in some instances stressdue to thermal gradients imposed across the assembly as it strikessuccessively arranged blades from a substantially tangential direction.More importantly, rotation of the wheel sets up centrifugal forces whichtend to throw the blades out from the wheel. These forces are ordinarilyrestrained by special attachments requiring expensive machinery, such asT-slots or pine-tree roots. In the present invention, a simpleinexpensive screw-thread is substituted for these special root forms. Itis extremely important that the individual blades be securely affixed tothe support member in order to avoid destruction of the machine shouldone or more of the blades become loose during operation.

SUMMARY OF THE INVENTION This invention relates to an improved wheelparticularly with regard to the manner in which the individual bladesare assembled and secured to the outer peripheral surface of theirassociated annular support or disc.

In accordance with the invention, the annular supporting disc isprovided with a plurality of circumferentially spaced tapped openings.The blades to be assembled with the disc each include an externallythreaded shank portion so that the blade can be readily assembled withthe tapped opening in the disc. In addition to the shank, there isprovided a body portion having a cross-sectional configuration in theform of an airfoil as is generally known in the art. Locatedintermediate the body portion and the shank portion is a relatively thinflat circular section integrally formed with the blade and referred tohereinatfer as a platform. In order that the individual blades may beassembled and be maintained against relative movement insofar as thedisc is concerned, the circular platform portion has in most instancesan arcuate edge section removed so as to provide a relief. The firstblade assembled with the disc is provided with opposed arcuate reliefs.The next adjacent blade is provided with a single relief as are each ofthe succeeding next adjacent blades until the last blade is ready forassembly. The last blade does not have an arcuate relief and serves tolock the cir- 3,565,547 Patented Feb. 23, 1971 cumferential array ofblades in tight engagement, free from relative circumferential movement.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows an impeller wheel, inperspective, constructed in accordance with this invention;

FIG. 2 illustrates the arrangement of a portion of the individual bladesrelative to one another upon assembly with a rotor; and

FIG. 3 is a partial, fragmentary view in perspective of three bladesconstructed in accordance with this invention prior to their assemblywith a supporting disc.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring more particularly tothe drawings for a description of one form of the invention, there isprovided a Wheel 10 of the type employed with turbomachines such asturbines utilizing water steam or gas as an input fluid. As is wellknown in the art, the energy present in the input field is converted tomechanical energy through the rotation of the impeller wheel under theinfluence of the stream of fluid being brought into contact, throughnozzles, with the individual blade members arranged about the peripheryof the wheel. It will be appreciated the wheel is attached to a shaftwhich in turn is attached to a device utilizing the mechanical energyprovided. Inasmuch as this invention is directed to the impeller wheelemployed in turbomachines it is not necessary to illustrate and describethe other components of the machine such as the casing, nozzle assembly,steam chest, or controls, all of which are well known in the art.

It is extremely important in turbomachinery of the kind described thatthe blades be securely mounted to the periphery of the wheel. Thepresent invention is directed to a blade configuration which readilylends itself to a secure connection with the supporting disc. The disc11 is provided with a plurality of circumferentially spaced radiallyextending tapped openings 12 extending inwardly of the impeller wheelfrom the outer peripheral surface. The openings are in turn providedwith a counterbore 13 for a purpose to be later described.

Arranged within the tapped openings are blade members 14 illustrated indetail in FIG. 3.

Referring more particularly to FIG. 3, each blade 14 is provided with anexternally threaded shank portion 16 and a body portion 18 arranged toextend within a passage in the machine through which the high energyfluid flows during operation of the machine. Disposed intermediate thebody portion 18 and the threaded shank portion 16 is a circular platformportion 20. The platform 20 is provided with a shape enabling it to bereceived within the counterbore 13 so as to provide a step-free surface,in the interest of more efficient fluid flow.

In accordance with the invention and with two exceptions, as will bemore clearly apparent, at least one arcuate edge section is removed fromeach platform 20 so as to provide a relief. In one instance it isnecessary to provide at least one of said blades 14a with opposedreliefs. In a second instance one of the blades 14b is unrelieved.

Considering the operation of the invention when it is desired toassemble the blades with the disc in order to provide a wheel for use ina turbomachine, the blade 14a having the opposed arcuate cut outsections or reliefs is initially assembled with an opening in the disc,not FIG. 2. Thereafter, a blade '14 having a single arcuate relief ismounted within an opening adjacent that accommodating the first blade.The arcuate relief section on blade 14a enables the second blade to belocated without interference into tight engagement with the threadedopening in the disc. The parts are so arranged and assembled that oncethe second blade is tightly fastened within its opposed arcuate reliefsections and the second to last blade 140 provided with a single arcuaterelief Which confronts the first blade when assembled, the last iblade14b does not require any relieved sections. In order to additionallysecure the last blade to the disc, a pin through the shank may beprovided if desired.

It will thus be apparent that a simple arrangement providing a threadedconnection between a series of blades and a supporting disc for use asan impeller wheel has been provided.

While I have described a preferred embodiment of the invention, it is tobe understood the invention is not limited thereto since it may beotherwise embodied Within the scope of the following claims.

I claim:

1. In a turbomachine, a rotor wheel Comprising an annular disc having aplurality of circumferentially spaced radially extending openingsarranged about the outer peripheral surface, a plurality of bladesdisposed within the openings, said blades including a shank portion, abody portion and a platform portion interposed between the body andshank portions, a first group of said blades 4 having one edge sectionof the platform portion removed, a blade having opposed edge sections ofsaid platform portion removed, and a blade having a substantiallycircular platform portion free of any relief defining a continuousarcuate edge.

2. In a turbomachine, an annular array of blade members arranged withina casing, at least one member having a threaded shank portion, a bodyportion and a platform portion, the said platform portion being providedwith an arcuate relief positioned to receive and engage a full edgesection of an adjacent blade of similar configuration so the bladesoiIer mutual resistance to rotation.

References Cited UNITED STATES PATENTS 2,038,670 4/1936 Noack416-219(UX) FOREIGN PATENTS 378,676 7/1923 Germany 416-207 892,7403/1962 Great Britain 4l6-219(W) EVERETTE A. POWELL, JR. Primary ExaminerUS. Cl. X.R. 416-2l2,219

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,565,54? ated February 23, 1971 Inventor(s) RAYMOND E. HANSEN It is certifiedthat error appears in the above-identified patent and that said LettersPatent are hereby corrected as shown below:

Column 2, line 21, "field" should read -fluid-- Column 2, line 65, "not"should read -note- Signed and sealed this 28th day of March 1972.

(SEAL) Attest:

EDWARD M.FIE'ICHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissionerof Patents

